If you wish to block all emails coming from a particular domain, log in to Roaring Penguin and follow the steps below.
1. Type the domain you wish to block in the box that appears under the Accept and Reject List heading.
2. Choose the Always reject mail from… option from the drop-down menu and click the Add button.
Note: Blocking a domain will block any email address associated with that domain from being able to send you emails. Emails from a blocked domain will not show up in your quarantine. The sender will instead receive a bounce back message stating that they are on a blacklist.